Biological Status of the West Branch Susquehanna River Watershed Following Long-Term Remediation of Abandoned Mine Drainage

Pennsylvania contains over 5,500 stream miles polluted with abandoned mine drainage (AMD) as a result of historic coal mining activities conducted prior to the 1977 federal Surface Mining Control and Reclamation Act.  The West Branch Susquehanna watershed, located in northcentral Pennsylvania, contains some of the Commonwealth’s most pristine and treasured waterways.  However, this watershed also contains nearly 1,200 miles of AMD polluted rivers and streams.  AMD remediation efforts have been ongoing throughout the watershed for over 20 years; however acidic waters continue to be the major limiting factor to biological recovery.  A thorough assessment of the biological conditions of the AMD-impaired streams had not been completed; therefore the purpose of this study was to assess the status of benthic macroinvertebrate populations throughout the West Branch Susquehanna River watershed’s AMD-impaired streams.  Water chemistry data and benthic macroinvertebrates were collected on 60 tributaries of the West Branch Susquehanna River during the spring of 2009.  The abundance and diversity of benthic macroinvertebrates was highly variable throughout the watershed due to differences in water chemistry, primarily pH and concentrations of aluminum and iron.  This variability allowed us to assess the relative tolerances of several taxa of macroinvertebrates to AMD pollution.  In addition, the community composition of benthic macroinvertebrates at the sample sites provided insight to the degree of biological recovery of the watershed.  These data provide a baseline to assess remediation efforts throughout the watershed and direct future remediation efforts.